The present invention relates to assessing the health status of a patient and, more particularly, to assessing the asthma status of a patient by providing an asthma status score and a confidence rating indicative of the score's reliability using continuous real-time data.
Asthma is an episodic chronic disease that involves disruption of normal respiratory function. One important objective of asthma therapy is preventing episodes of extreme worsening of respiratory function (i.e. asthma attacks) that can lead to hospitalization and even death. To assist in these prevention efforts, the National Institute of Health (NIH) has recommended that asthma sufferers take an Asthma Control Test (ACT) that gives them an idea of how well their asthma has been controlled in the preceding four weeks. The ACT consists of five questions relating to asthma symptoms to which a patient inputs scores that are combined into a total score. A score below 20 (out of a maximum of 25) indicates that the patient's asthma is not well controlled.
Unfortunately, studies have shown that use of the ACT has had only minimal impact in controlling asthma. One problem with the ACT is data reliability. The ACT relies entirely on self-reporting of asthma symptoms. A patient may fail to accurately perceive or assess his or her symptoms, which can cause the patient to delay seeking medical treatment until it is too late. Moreover, the ACT does not take into account the presence or absence of asthma triggers in the patient's environment (e.g. airborne particles, humidity, temperature, etc.). Another problem with the ACT is that the test is taken too infrequently. With more severely affected asthma patients, the ACT is typically performed twice a day. However, the risk of an asthma attack can change in real-time as a patient moves from one environment to another during normal daily activities.
Other asthma scoring approaches have been devised, including computerized approaches that score the asthma status of a patient based at least in part on data collected by sensors mounted on or near the body of a patient. While these approaches rely on reasonable data reliability and increased frequency of testing, they have used a limited set of health attributes and are not known to generate confidence ratings for asthma status scores that indicate the reliability of the scores.